Police are appealing for witnesses and dashcam footage following a fatal collision at Broadbridge Heath.
Emergency services were called to the junction of the A264 and A24 northbound after a vehicle left the slip road carriageway at about 7.45pm on Sunday, April 17.
The incident involved a single vehicle, a silver Peugeot 208.
Tragically, an 80-year-old man from Peaslake, Surrey, was pronounced dead at the scene. His next of kin have been informed.
A 69-year-old woman sustained life-threatening injuries and remains at the Royal Sussex County Hospital in a critical but stable condition.
Anyone who witnessed the incident or who has footage of the Peugeot in the minutes before the incident is asked to email: collision.appeal@sussex.police.uk and quote Operation Linford.